St Helens are six points clear at the top after outclassing Tigers 32-16 in the Magic Weekend finale at Anfield yesterday.
They looked untouchable in Liverpool and are on course to finish as league leaders for the second successive year.
But Tigers lost to Leeds Rhinos in the 2017 Grand Final after topping the league by 10 points and Saints did not reach Old Trafford last year, after losing to Warrington Wolves at the semi-final stage, so Powell believes it is still game on.
Tigers are fifth, 14 points behind Saints and he admitted they are too good at the moment, but things could change.
“They put Warrington, who are second, to the sword a few weeks ago and they are a great side,” he noted of Saints.
“They are playing really well at the moment. Whether that goes all the way to the Grand Final, who knows?
“You’d have thought in 2017 we’d have finished that off and you’d have thought last year that they would have finished it off.
“It doesn’t always happen the way it should.”
Powell reckons Tigers’ challenge is to hang on in the top-five and, when they get injured players back, he is confident they can be a force towards the end of the campaign and in the play-offs.
Castleford have no game this weekend as Super League takes a break for the Coral Challenge Cup quarter-finals and that will give their casualties extra time to recover.
Tigers’ next match is at home to Huddersfield Giants on Friday, June 7 and Powell said: “I am hopeful on Oliver Holmes and Junior Moors.
“They are getting a bit better.
“Jamie Ellis [who has not played this season] potentially could be back in the mix in the next few weeks.
“Michael Shenton is four or five weeks away and Alex Foster needs an operation so he is going to be gone for a while which is disappointing and tough on him.
“I am not 100 per cent certain, but we might start to get three or four back.”